1. Field of the Invention
The present invention relates to a zinc oxide based sputtering target favorably applied to film formation of a zinc oxide based transparent electrically conductive film, a method for manufacturing the zinc oxide based sputtering target, a zinc oxide based transparent electrically conductive film, a method for manufacturing the zinc oxide based transparent electrically conductive film, and an electronic apparatus including the zinc oxide based transparent electrically conductive film.
2. Description of the Related Art
As for transparent electrically conductive films for electronic apparatuses, e.g., liquid crystal displays, organic EL displays, and touch panels, indium tin oxide (ITO) has been previously widely used, in which indium oxide (In2O3) has been doped with tin oxide (SnO2). However, development of a material alternative to ITO has become urgent because of a jump in ITO prices along with exhaustion of ITO in recent years. Among the materials alternative to ITO, zinc oxide (ZnO) based transparent electrically conductive materials have been noted because of rich resources and low costs, so that research has been conducted actively.
As for a method for forming the zinc oxide based transparent electrically conductive film, various methods, e.g., a sputtering method, a pulse laser deposition (PLD) method, an ion plating method, and a vacuum evaporation method, are in the public domain. Among them, the sputtering method has been adopted predominantly on the grounds that high speed film formation can be conducted, and so on.
In the past, as for a sputtering target to form the zinc oxide based transparent electrically conductive film exhibiting low resistance and excellent transparency by the sputtering method, an AZO target, in which zinc oxide (ZnO) is doped with 2 percent by weight of aluminum oxide (Al2O3), has been used (refer to, for example, Japanese Unexamined Patent Application Publication No. 7-258836 and Japanese Unexamined Patent Application Publication No. 2006-200016).